Leases - Undiscounted Cash Flows (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Operating Leases
2022	$ 944
2023	974
2024	894
2025	866
2026	766
Thereafter	5,307
Total minimum lease payments	9,751
Less: amount of lease payments representing interest	(1,992)
Present value of future minimum lease payments	7,759
Less: current obligations under leases	(703)	$ (678)
Noncurrent operating lease liabilities	7,056	5,713
Finance Leases
2022	324
2023	286
2024	369
2025	232
2026	168
Thereafter	636
Total minimum lease payments	2,015
Less: amount of lease payments representing interest	(179)
Present value of future minimum lease payments	1,836
Less: current obligations under leases	(280)	(289)
Long-term lease obligations	$ 1,556	$ 894